Portable navigation devices (PNDs) that include GPS (Global Positioning System) signal reception and processing functionality are well known and are widely employed as in-car or other vehicle navigation systems.
In general terms, a modern PND comprises a processor, memory (at least one of volatile (e.g. RAM) and non-volatile (e.g. ROM), and commonly both), and map data stored within said memory. The processor and memory cooperate to provide an execution environment in which a software operating system may be established, and additionally it is commonplace for one or more additional software programs to be provided to enable the functionality of the PND to be controlled, and to provide various other functions.
Typically these devices further comprise one or more input interfaces that allow a user to interact with and control the device, and one or more output interfaces by means of which information may be relayed to the user. Illustrative examples of output interfaces include a visual display and a speaker for audible output. Illustrative examples of input interfaces include one or more physical buttons and a microphone for detecting user speech. The buttons may be configured, for example, to power the PND on or off or to control operation or other features of the device and need not necessarily be on the PND itself but could be on a steering wheel or another part of the vehicle in circumstances where the device is built into a vehicle. In a particularly preferred arrangement the output interface display may be configured as a touch sensitive display (by means of a touch sensitive overlay or otherwise) to additionally provide an input interface by means of which a user can operate the device by touch.
Devices of this type will also often include one or more physical connector interfaces by means of which power and optionally data signals can be transmitted to and received from the device, and optionally one or more wireless transmitters/receivers to allow communication over cellular telecommunications and other signal and data networks. PND devices of this type also typically include a GPS antenna by means of which satellite-broadcast signals, including location data, can be received and subsequently processed to determine a current location of the device.
The PND device may also include electronic gyroscopes and accelerometers which produce signals that can be processed to determine the current angular and linear acceleration, and in turn, and in conjunction with location information derived from the GPS signal, velocity and relative displacement of the device and thus the vehicle in which it is mounted. Typically such features are most commonly provided in in-vehicle navigation systems, but may also be provided in PND devices if it is expedient to do so.
The utility of such PNDs is manifested primarily in their ability to determine a route between a first location (typically a start or current location) and a second location (typically a destination). These locations can be input by a user of the device, by any of a wide variety of different methods, for example by postcode, street name and house number, previously stored “well known” destinations (such as famous locations, municipal locations (such as sports grounds or swimming baths) or other points of interest), and favourite or recently visited destinations.
Typically, the PND is enabled by software for computing a “best” or “optimum” route between the start and destination address locations from the map data. A “best” or “optimum” route is determined on the basis of predetermined criteria and need not necessarily be the fastest or shortest route. The selection of the route along which to guide the driver can be very sophisticated, and the selected route may take into account existing, predicted and dynamically and/or wirelessly received traffic and road information, historical information about road speeds, and the driver's own preferences for the factors determining road choice (for example the driver may specify that the route should not include motorways or toll roads).
In addition, the device may continually monitor road and traffic conditions, and offer to or choose to change the route over which the remainder of the journey is to be made due to changed conditions. Real time traffic monitoring systems, based on various technologies (e.g. mobile phone data exchanges, fixed cameras, GPS fleet tracking) are being used to identify traffic delays and to feed the information into notification systems.
PNDs of this type may typically be mounted on the dashboard or windscreen of a vehicle. In addition, the functionality of PNDs may be embodied in a navigation device that is built into a vehicle, for example as part of an on-board computer of the vehicle radio or indeed as part of the control system of the vehicle itself. The navigation device may also be part of a hand-held system, such as a PDA (Portable Digital Assistant) a media player, a mobile phone or the like, and in these cases, the normal functionality of the hand-held system is extended by means of the installation of software on the device to perform both route calculation and navigation along a calculated route.
Route planning and navigation functionality may also be provided by a desktop or mobile computing resource running appropriate software. For example, the Royal Automobile Club (RAC) provides an on-line route planning and navigation facility at http://www.rac.co.uk, which facility allows a user to enter a start point and a destination whereupon the server to which the user's PC is connected calculates a route (aspects of which may be user specified), generates a map, and generates a set of exhaustive navigation instructions for guiding the user from the selected start point to the selected destination. The facility also provides for pseudo three-dimensional rendering of a calculated route, and route preview functionality which simulates a user travelling along the route and thereby provides the user with a preview of the calculated route.
In the context of a PND, once a route has been calculated, the user interacts with the navigation device to select the desired calculated route, optionally from a list of proposed routes. Optionally, the user may intervene in, or guide the route selection process, for example by specifying that certain routes, roads, locations or criteria are to be avoided or are mandatory for a particular journey. The route calculation aspect of the PND forms one primary function, and navigation along such a route is another primary function.
During navigation along a calculated route, it is usual for such PNDs to provide visual and/or audible instructions to guide the user along a chosen route to the end of that route, i.e. the desired destination. It is also usual for PNDs to display map information on-screen during the navigation, such information regularly being updated on-screen so that the map information displayed is representative of the current location of the device, and thus of the user or user's vehicle if the device is being used for in-vehicle navigation.
An icon displayed on-screen typically denotes the current device location on the map, and it is usual for the icon to be centred with on the map to provide a good view of roads in the vicinity of the current device location. Icons representing the location of other points of interest (such as petrol stations, airports, recreation facilities and such like) on the map may also be displayed. Additionally, navigation information may be displayed, optionally in a status bar above, below or to one side of the displayed map information, examples of navigation information include a distance to the next manoeuvre that a user is required to take to continue along a calculated route, the nature of that manoeuvre possibly being represented by a further icon suggestive of the particular type of manoeuvre, for example a left or right turn. The navigation function also determines the content, duration and timing of audible instructions by means of which the user can be guided along the route. As can be appreciated a simple instruction such as “turn left in 100 m” requires significant processing and analysis. As previously mentioned, user interaction with the device may be by a touch screen, or additionally or alternately by steering column mounted remote control, by voice activation or by any other suitable method.
A further important function provided by the device is automatic route re-calculation in the event that: a user should deviate from a previously calculated route during navigation (either by accident or intentionally); real-time traffic conditions dictate that an alternative route would be more expedient and the device is suitably enabled to recognize such conditions automatically, or if a user actively causes the device to perform route re-calculation for any reason.
It is also known to allow a route to be calculated with user defined criteria; for example, the user may prefer a scenic route to be calculated by the device, or may wish to avoid any roads on which traffic congestion is likely, expected or currently prevailing. The device software would then calculate various routes and weigh more favourably those that include along their route the highest number of points of interest (known as POIs) tagged as being for example of scenic beauty, or, using stored information indicative of prevailing traffic conditions on particular roads, order the calculated routes in terms of a level of likely congestion or delay on account thereof. Other POI-based and traffic information-based route calculation and navigation criteria are also possible.
Although the route calculation and navigation functions are fundamental to the overall utility of PNDs, it is possible to use the device purely for information display, or “free-driving”, in which only map information relevant to the current device location is displayed, and in which no route has been calculated and no navigation is currently being performed by the device. Such a mode of operation is often applicable when the user already knows the route along which it is desired to travel and does not require navigation assistance.
Navigation devices such as the TomTom 720T model PND manufactured and supplied by TomTom International B.V., and the Carminat TomTom system that is available as a built-in component of Renault vehicles, each provide a reliable means for enabling users to navigate from one position to another—although the accuracy of any given calculated route will depend to some extent on the accuracy of the data stored in the device on which the route calculation is based.
In general terms, map data tends to change relatively slowly over time as new roads are built, and as such it is reasonably likely that newly obtained map data will remain current for a reasonable amount of time.
However, as other types of data are included in the route calculation process, so the efficacy of a given calculated route becomes more dependent on the accuracy of the data stored in the device. For example, some navigation devices permit routes to be calculated using information concerning currently prevailing traffic congestion, but as this information changes rapidly the accuracy and/or efficacy of a given calculated route will vary significantly over time. As an illustration, it is immediately apparent that a route through a city centre which was calculated on the basis of traffic congestion at 9.00 am may well not be the best route later on in the day.
To this end it is advisable for the data stored in the navigation device to be regularly updated, and in general terms it is true to say that the more volatile the data used to calculate a route, the more important it becomes to update the data stored in the device.
Portable navigation devices are currently updated either by plugging the device into a computer and downloading updates to the device via the internet, or by updating the device wirelessly over the mobile telephone network. For navigation devices that are permanently built-into a vehicle, the data stored on the device can typically be updated by downloading updates onto a suitable data storage device and then uploading that data from the storage device to the navigation device, or again by downloading data to the navigation device over the mobile telephone network.
Downloading data to a PND via the internet, and uploading data from a storage device to a built-in navigation device each take some time and can therefore be inconvenient for some users. Downloading data to a navigation device via the mobile telephone network is relatively slow, and hence is not a viable solution for large amounts of data (such as a new digital map). Downloading data over a mobile network can also incur considerable charges if the user is not a subscriber to an all-inclusive data plan.
It would be advantageous, therefore, if a means could be devised whereby the content of navigation devices could be easily, inexpensively and quickly be updated.